In order to improve radio communications it has been proposed to use receive diversity wherein a number of fully or partially de-correlated signals received from the same source by different antennas are combined to provide a more reliable received signal.
The use of receive diversity is of increasing practical interest and is being introduced to more and more applications and is specifically being proposed to also be used in small portable battery powered communication units. For example, whereas the use of receive diversity has previously been limited to base stations of cellular communication systems, the intention is now to also provide some user equipments with multiple antennas in order to obtain receive diversity benefits. Specifically, 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution), 3GPP HSPA+ (High-Speed Packet Access) and 3GPP GERAN (GSM (Global System for Mobile communication) EDGE (Enhanced Data rates for GSM Evolution) Radio Access Network) Evolution include the use of receive diversity for the mobile stations.
However, a problem associated with the use of receive diversity is that the additional processing and functionality introduces additional computational demands and resource usage. In particular, the additional processing and functionality increases the power consumption and results in a reduced battery life for battery driven devices.
In order to address this problem, it has been proposed to switch receive diversity on or off depending on the experienced propagation conditions. Thus, receive diversity may be switched on if the propagation conditions deteriorate such that the receive quality of the received signal falls below a threshold. Similarly, if the propagation conditions improve during receive diversity operation, the diversity operation may be switched off when the receive quality exceeds a given threshold.
However, although such an approach may provide acceptable operation and reduce resource consumption in many scenarios, it tends to be suboptimal or insufficient in many cases. The approach may result in suboptimal usage of receive diversity thereby resulting in reduced receive quality and/or increased resource consumption.
Hence, an improved approach would be advantageous and in particular a system allowing increased flexibility, reduced resource usage, increased battery life, reduced power consumption, improved receive quality and/or improved performance would be advantageous.